I read somewhere that the Blessed Mother promised that family whom we prayed for would be saved if we prayed a certain prayer or participated in a certain devotion. I can't remember what it is.

Answer by Catholic Answers on 06-16-2014:

Anon--

I don't know which prayer or devotion you are thinking of either, but I can assure you that praying "a certain prayer" or participating in "a certain devotion" is not a guarantee of salvation, for yourself or anyone else. Rather those who pray certain prayers or participate in certain devotions with such intentions are instead engaging in superstition and treating the prayers like magical incantations.

Any prayer said sincerely, with love for God and devotion to his Mother, is fruitful for the salvation of souls. What matters is the love and devotion, not the words of the prayer or the formula of the devotion.